when did common core start

Common Core started in 2009 as a standards-writing initiative, and the first state adoptions began in 2010.

Timeline

• 2009: The Common Core standards were drafted and launched by the National Governors Association and the Council of Chief State School Officers.

• 2010: States began adopting the standards, with Kentucky among the first.

In plain terms

If you mean when Common Core first began , the best answer is 2009. If you mean when it started showing up in classrooms through state adoption, that was 2010 onward.

TL;DR: Common Core began in 2009 and spread through state adoption starting in 2010.